Abstract
Studies on persistent-polarization/memory-type effect in a Ag+ ion conducting system : "a quenched [0.75AgI:0.25AgCl] mixed-system/solid-solution", recently investigated in the present laboratory as a better alternate to conventional host-salt AgI, are reported. A constant de polarizing field (similar to 0.5 V) was applied across the sample, placed in the cell configuration : C/[0.75AgI:0.25AgCl]/C. The electronically conducting graphite (C) behaves as a blocking electrode for mobile Ag+ ions. To study the charge fixation persistent-polarization/memory-type effect due to thermal stimulation, sample pellet was placed in a furnace at similar to 200 degrees C (i.e. well above the beta --> alpha-like phase transition temperature of the material) and polarized in two different ways: (1) polarization field was applied for 10 min, then removed; (2) polarization field was kept on and the sample was cooled slowly From 200-27 degrees C by switching off the: furnace, then the field was removed. The potential gradient developed across the sample pellet due to accumulation/polarization of Ag+ ions, was measured as a function of temperature during several heating/cooling cycles and over a long span of time ranging from few hours to several hundred hours. All the measurements were carried out instantly to avoid possibility of any discharge. This instant potential has been referred to as peak potential rb. The study revealed that the polarization states persisted for long time. It was also observed that the effect of persistent polarization is far superior in the sample polarized by method (2). The phenomenon of persistent-polarization in this system indicated "as if the mobile Ag+ ions retain the memory of their polarization state at a particular temperature". This kind of effect has been observed earlier in AgI also.